Is relation t a function? is the inverse of relation t a function?
relation t:

x; 0 , 2 , 4 , 6
y; -10 , -1 , 4 , 8

relation t is not a function. the inverse of relation t is not a function.

relation t is a function. the inverse of relation t is a function.

relation t is a function. the inverse of relation t is not a function.

relation t is not a function. the inverse of relation t is a function.

( i think its a, but not sure ? )